Georgia also recalled its ambassador to Russia "for consultations", its foreign ministry said.

Shortly after Saakashvili's statement, the main opposition television station Imedi, which had broadcast coverage of the protests, said it had been stormed by Georgian special forces, then went off the air.

Violence

In the clashes on Wednesday, tear gas enveloped parliament after riot police advanced towards the crowd, pushing people back with shields and beating some with truncheons.

The protesters accuse Saakashvili of economic mismanagement and corruption [AFP]

Scattered fist fights broke out between police and protesters.

Demonstrators retreated down Tbilisi's main avenue but several thousand opposition supporters rallied later in another section of Tbilisi, only to have the protest broken up again by riot police using water cannon and firing rubber bullets.

Protesters pelted police with rocks from a bridge.

Levan Gachechevadze, an opposition leader, said police did not use truncheons during the initial sweep but had kicked him.

"They beat me, and Saakashvili will be beaten, too," he told the privately owned Imedi television after he returned to the protest.

The number of protesters increased rapidly to about 5,000 people and units of black-clad riot police were deployed after the conventional police force was overwhelmed.

fist fights broke out between police and protesters [AFP]

The protests, in their sixth day, mark the biggest challenge to Saakashvili since his landslide election four years ago.

The protesters initially called for changes in the dates of planned elections and in the electoral system, but later made Saakashvili's resignation their central demand.

They accused Saakashvili of economic mismanagement and corruption - accusations he rejects.

Gigi Ugulava, Tbilisi's mayor, defended the action by police, saying: "I was listening to one of the opposition leaders who was saying proudly they planned to pitch tents and set up a tent town in Tbilisi.

"What we did is stop this because it is the will of the people not to have a tent town in Tbilisi."